Dr Chen Song


School of Psychology

Research summary

Brain Complexity -  Organizing Principles of the Brain

Our  brain is highly complex and is composed of many regions, each serving a unique  set of functions. What enables different brain regions to have different  functions? Is that because of their inherent structural differences? If so, how  do structurally different brain regions get to work coordinately? To understand  the organizing principles of the brain, we study (A) how different brain  regions differ structurally, (B) how the structural differences underlie the  functional differences, and (C) whether the empirically observed function of a  brain region is indeed what the structure of this region is most optimal for.

From Brain Complexity  to Behavioral Complexity - Variability across Individuals

Mirroring  the brain complexity, our behavior and consciousness are highly complex. For  example, our perception of an image is rarely a truthful reflection of the  physical features of the image, but is instead biased by the contexts in which  the image appears, and our susceptibility to such contextual illusions can vary  over ten folds across healthy individuals. How does behavioral complexity  relate to brain complexity? What brain properties give rise to the variability  in conscious experiences across individuals? To understand the links between  brain and consciousness, we study (A) how different individuals differ in their  brain structure, (B) how the inter-individual differences in brain structure  affect neural function, and (C) lead to inter-individual differences in  behavior and consciousness.

Brain and Behavioral  Plasticity - Impacts of Learning and Sleep

Our  behavior exhibits high adaptability and plasticity, and so is our brain. The  changes in brain structure not only occur when we are awake and learning, but  also continue as we fall asleep. To understand the mechanisms of brain and  behavioral plasticity, we study (A) how learning and sleep interact to  influence brain and behavior, (B) whether different mechanisms of brain  plasticity may be at play during wake versus sleep, and (C) whether the  contrast between wake and sleep in brain plasticity may hold key to our  behavioral plasticity and our ability to constantly learn and adapt.

Please visit my  website BRAIN COMPLEXITY & CONSCIOUSNESS for details of projects, publications, and funding.

Teaching summary

I  give guest lecture on MSc in Neuroimaging Module Perception and Action (PST507).


PhD in Neuroscience, University College London
MSc in Cognitive Neuroscience, University College London
BSc in Biomedical Engineering, Shanghai  Jiao Tong University


2017 - Present: Cardiff University Brain Research Imaging  Centre, Cardiff University, UK.
2015 - 2017: Wisconsin Institute for Sleep and Consciousness,  University of Wisconsin-Madison, USA
2013 - 2015: Mullard Space Science Laboratory, University  College London, UK
2009 - 2013: Wellcome Trust Centre for Neuroimaging,  University College London, UK
2009 - 2013: Institute of Cognitive Neuroscience, University  College London, UK
2007 - 2007: Max Planck Institute for Mathematics in the  Science, Germany
2006 - 2009: Institute of Neuroscience,  Chinese Academy of Sciences, China

Honours and awards


2017: Sir Henry Wellcome Fellowship, by Wellcome Trust
2017: Marie Curie COFUND Fellowship, by European Commission  and Welsh Government
2016: British Neuroscience Association Award, by British  Neuroscience Association
2015: Chinese Government Award for Outstanding Scholars  Abroad, by Chinese Government
2014: Engineering Young Entrepreneurs Scheme Award, by EPSRC
2013: Cross-disciplinary Research Scholarship, by University  College London
2012: Enterprise Scholarship, by University College London
2010: Overseas Research Scholarship, by University College  London
2010: Brain Research Trust Scholarship, by Brain Research  Trust
2008: Sigma Xi Grants-in-Aid of Research Award, by Sigma Xi  Society
2007: DAAD-IAESTE Award, by German Academic Exchange Service
2006: Excellent Academy Scholarship, by Shanghai Jiao Tong  University
2005: National Scholarship, by Chinese  Government

Research topics and related papers

Brain Complexity - Organizing Principles of the Brain

Aims: Our  brain is highly complex and is composed of interconnected brain regions. The  interconnected nature of the brain poses great challenges for studying brain  function. In essence, the activation of a brain region in a cognitive task is  driven by all regions that this region connects with, and it is difficult to  tell which ones of these regions, or all of them, are responsible for this  cognitive task. Thus, looking at brain activity alone is not enough for  understanding brain function. We take a different approach, looking at what  enables different brain regions to have different functions at first place -  their structural differences. We study how different brain regions differ  structurally and how their structural differences underlie their functional  differences.

Progress: Our  research reveals a systematic structural difference between sensory cortices  and prefrontal cortex. We found that sensory cortices have topographically  ordered wiring, high information capacity, but low flexibility; by contrast,  frontal cortex has random wiring, low information capacity, but high  flexibility. These structural differences match their functional differences:  the high information capacity of sensory cortices is well suited for  uni-sensory processing and multisensory integration, whereas the high  flexibility of prefrontal cortex is well suited for executive control. Our  research also reveals a reverse correlation between the sizes of sensory  cortices and prefrontal cortex. We found that individuals with large sensory  cortices have small prefrontal cortex, and vice versa. This structural  trade-off challenges the traditional view that the sizes of different brain  regions simply scale with the overall brain size, and hints towards a  functional trade-off between low-level sensory domains and high-level cognitive  domains.

From Brain Complexity to Behavioral Complexity - Variability  across Individuals

Aims:  Mirroring the brain complexity, human behavior and conscious experiences  exhibit high complexity. The complexity is present not only in high-level  cognitive domains such as introspection, planning, reasoning, but also in  low-level sensory domains. For example, our perception of an image is rarely a  truthful reflection of the physical features of the image, but is instead  biased by the contexts in which the image appears and by our experience or  expectation. How does behavioral complexity relate to brain complexity?  Research on brain-behavior relationships often focuses on the similarity across  individuals in brain and behavior. We instead take the opposite approach,  studying how individual differences in brain complexity relate to individual  differences in behavioral complexity.

Progress: Our  research reveals that a behaviorally advantageous visual cortex has the  structure of a large surface area but a small thickness. We found that  individuals with larger visual cortex can discriminate finer visual  details and experience weaker visual illusions; by contrast, thicker visual  cortex is associated with poorer vision. Critically, we found that the impacts  of brain structure on visual perception are mirrored in neural  function: neurons in larger or thinner visual cortex have more precise  coding. To explain our findings, we built a computational model of visual  cortex. The model suggests that enlarging the cortical surface area increases  the number of cortical units, whereas shortening the cortical thickness  decreases the processing delays within cortical units; either way, the structure  supports higher functionality. The model predicts correlations between visual  perception and intrinsic connectivity, oscillation frequency, or  neurotransmitter level of visual cortex, which we tested and all confirmed.

Brain and Behavioral Plasticity - Impacts of Learning and  Sleep

Aims: A remarkable feature of human brain and behavior is their adaptability and  plasticity. The environmental inputs we receive while awake can induce changes  in brain and behavior, via which we learn and adapt. Even when we are asleep  and disconnected from the environment, the brain is still highly active, and  the sleeping brain activity can induce brain structural changes via  activity-dependent plasticity. Research on brain plasticity often focuses on  the net changes across the sleep-wake cycle. We instead suggest that opposite  mechanisms of brain plasticity may be at play during wake versus sleep, and the  contrast between wake and sleep in brain plasticity may hold key to our  behavioral plasticity and our ability to constantly learn and adapt.

Progress: We  are currently testing how the brain structure and function change across the  sleep-wake cycle, and whether these changes can account for the declines in  behavioral performances with the time awake and the improvements in behavioral  performances after sleep. While awake, the brain is constantly perturbed by  inputs from the environment, which often induce activities incongruent with the  brain's wiring. By contrast, during sleep, the brain is driven by itself, and  its activity is congruent with its wiring. We hypothesize that the  environmental-driven nature of waking brain activity will add noise to the  brain's wiring and impair its efficiency, whereas the self-driven  nature of sleeping brain activity will help to reinstate the wiring  efficiency. We are also testing how learning and sleep interact to change  brain structure and function. We hypothesize that, if the learning is  ecologically beneficial and improves the brain’s wiring efficiency, it will get  consolidated after sleep, and if not, it will be weakened by sleep.


8. Influence  of Sleep on Human Brain Structure
Funding: Wellcome Trust
Institute: Cardiff University  Brain Research Imaging Centre
Wisconsin Institute  for Sleep and Consciousness, University of Wisconsin-Madison
Amount: £250,000
Duration: 03/2018-02/2022

7. Improving  Human Cognition and Brain Structure by Manipulating Sleep Brain Activity
Funding: European  Commission, Welsh Government, Cardiff University
Institute: Cardiff  University Brain Research Imaging Centre
Amount: £360,694
Duration: 09/2017-08/2020

6. Dynamics  of Solar Coronal Activity versus Human Brain Activity
Funding: University College  London
Institute: Mullard Space  Science Laboratory, University College London
Amount: £36,976
Duration: 09/2013-08/2015

5.  Predicting Aesthetic Preferences from Human Brain Structure
Funding: University  College London
Institute: Centre for  Entrepreneurship and Business Interaction, University College London
Amount: £4,000
Duration: 09/2013-12/2013

4. Neural  Basis of Individual Differences in Visual Perception
Funding: University  College London
Institute: Institute of  Cognitive Neuroscience, University College London
Amount: £54,985
Duration: 09/2010-08/2013

3. Context,  Consciousness and the Brain
Funding: Brain  Research Trust
Institute: Wellcome Trust  Centre for Neuroimaging, University College London
Amount: £109,828
Duration: 09/2010-08/2013

2. Binocular  Rivalry and Visual Consciousness
Funding: Sigma-Xi  Society
Institute: Institute of  Neuroscience, Chinese Academy of Sciences
Amount: $600
Duration: 07/2008-06/2009

1. Modelling  Top-down Influences in Visual Processing
Funding: German  Academic Exchange Service
Institute: Max Plank  Institute for Mathematics in the Sciences
Amount: €2,400
Duration: 07/2007-10/2007

Research group


External collaborators

Prof. Geraint Rees, Wellcome Trust Centre for Neuroimaging, University  College London, UK.
Prof. Giulio Tononi, Wisconsin Institute for Sleep and Consciousness,  University of Wisconsin-Madison, USA.
Prof. Haishan Yao, Institute of Neuroscience, Chinese Academy of  Sciences, China.
Prof. Haidong Lu, State Key Laboratory of Cognitive Neuroscience and  Learning, Beijing Normal University, China.
Prof. Juergen Jost, Max Plank Institute for Mathematics in the Sciences,  Germany.
Dr. Ryota Kanai, Sackler Centre for Consciousness Science, Sussex  University, UK.
Dr. Melanie Boly, Department of Neurology, University of  Wisconsin-Madison, USA.
Dr. Tobias Elze, Schepens Eye Research Institute, Harvard University,  USA.

Postgraduate research interests

If you are interested in applying for a PhD, or for further information  regarding my postgraduate research, please contact me directly (contact details available on the 'Overview' page), or submit a formal application here.

The joy of science lies very much in the collaboration between  the like-minded, and the debate among the different-minded. We welcome anyone interested  in our research to join or collaborate. We have PhD funding for 2018/19  intake and will be advertising soon. Please feel free to  contact me at SongC5@cardiff.ac.uk for any inquiry, or visit my website BRAIN COMPLEXITY & CONSCIOUSNESS for details of projects, publications, and funding.

Media activities